The hard part here is that Matt was not being specific in his response. Yes, he was responding to the question that read:

Matt, can you please tell us exactly what to fix now then so we are not caught off guard? Don't give us the secret sauce, just be transparent and say "watch your linking text" or "check your HTML for inadvertent alt attributes with keywords in them" or "delete all your old links on "put-it-there-yourself" pages (or nofollow them)" or whatever this new penguin eats :-) That would be awesome transparency that does not give anything new away, just focuses our efforts. Thanks!

But is that response a general response or a Penguin specific response?

Only Matt knows for sure, but I thought I point it out.

I did ask Matt what he was referring to specifically but I did not yet receive a response.